In the technical field of electrovacuum, the pyrolytic graphite gate electrode is the most ideal material for the gate electrode of large-scale emission tube, in particular, the high-power emission triode/tetrode relating to the anode cooled by a hyper vapotron. By producing the gate electrode from pyrolytic graphite, the deformation of the gate electrode, which can be induced by the mechanical stress caused by the butt-welding, welding of the gate electrode cap, matching of the support or the like, is completely eliminated. At the same time, this gate electrode has good thermal properties, mechanical properties, conductivity, and vacuum properties.
However, in the production process of the pyrolytic graphite gate electrode, paraffin wax, dusts and other impurities exist on the surface of the gate electrode. During the gas exhausting process of the electron tube, these substances are decomposed due to the heating of the electrode, and release a large amount of gas. Or, in later application, these substances are gradually decomposed or evaporated, which makes the vacuum degree in the tube worse. The high-voltage-withstanding ability of the electron tube is seriously affected, and even the electron tube becomes a waste product.
Therefore, before the graphite gate electrode is fixed into a tube, it must be subjected to a cleaning treatment. Without the cleaning treatment, the graphite gate electrode in exhausting stage will release gas from the gate electrode, so that the vacuum degree cannot be increased, or the current at the burrs on the gate electrode is too large, and thus a waste product is produced.
In prior art, the surface treating process for a graphite gate electrode comprises the steps of immersing the graphite gate electrode into gasoline for 12 h, washing the graphite gate electrode with tap water to clean it, then boiling it with deionized water for 30 min, thereafter, cleaning it with ultrasonic treatment for 1 h. Thus, the process of the cleaning treatment for the surface of the graphite gate electrode is achieved. The gasoline can only serve for de-oiling, but not for removing the dusts and burrs on the surface of the graphite gate electrode.
Additionally, in prior art, the surface treating process for the graphite gate electrode has a relatively long duration, relatively low de-oiling rate (that is, cannot completely remove the gasoline). Additionally, gasoline is inflammable and is not safe during the application.